U.S. patent number 8,413,513 [Application Number 12/934,831] was granted by the patent office on 2013-04-09 for ultrasonic testing method and equipment therefor.
This patent grant is currently assigned to Nippon Steel & Sumitomo Metal Corporation. The grantee listed for this patent is Masami Ikeda, Yoshio Ueda, Masaki Yamano. Invention is credited to Masami Ikeda, Yoshio Ueda, Masaki Yamano.
United States Patent |
8,413,513 |
Ueda , et al. |
April 9, 2013 |
Ultrasonic testing method and equipment therefor
Abstract
An ultrasonic testing equipment includes a linear array
ultrasonic probe in which a plurality of transducers are arranged
in a direction orthogonal to the rolling direction of a test object
and a signal processing unit. The signal processing unit executes
following (1) to (6). (1) Generating an aperture synthetic image of
testing signals of each section of the test object. (2) Generating
a maximum value distribution of testing signals in the arrangement
direction of transducers. (3) Calculating the width of a defect in
each section based on the maximum value distribution. (4)
Generating a maximum value distribution of the testing signals in
the rolling direction based on the maximum value distribution of a
plurality of sections of the test object. (5) Calculating the
length of the defect based on the maximum value distribution of the
testing signals in the rolling direction. (6) Calculating the area
of the defect based on the calculated defect length and the
calculated defect width of each section.
Inventors: |
Ueda; Yoshio (Osaka,
JP), Yamano; Masaki (Osaka, JP), Ikeda;
Masami (Osaka, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Ueda; Yoshio
Yamano; Masaki
Ikeda; Masami |
Osaka
Osaka
Osaka |
N/A
N/A
N/A |
JP
JP
JP |
|
|
Assignee: |
Nippon Steel & Sumitomo Metal
Corporation (Tokyo, JP)
|
Family
ID: |
41113731 |
Appl.
No.: |
12/934,831 |
Filed: |
March 24, 2009 |
PCT
Filed: |
March 24, 2009 |
PCT No.: |
PCT/JP2009/055743 |
371(c)(1),(2),(4) Date: |
December 13, 2010 |
PCT
Pub. No.: |
WO2009/119539 |
PCT
Pub. Date: |
October 01, 2009 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20110113885 A1 |
May 19, 2011 |
|
Foreign Application Priority Data
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|
|
|
|
Mar 27, 2008 [JP] |
|
|
2008-082782 |
|
Current U.S.
Class: |
73/602 |
Current CPC
Class: |
G01N
29/265 (20130101); G01N 29/069 (20130101); G01N
29/262 (20130101); G01N 2291/106 (20130101); G01N
2291/2632 (20130101) |
Current International
Class: |
G01N
29/11 (20060101); G01N 29/40 (20060101) |
Field of
Search: |
;73/602 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
09-145686 |
|
Jun 1997 |
|
JP |
|
09145686 |
|
Jun 1997 |
|
JP |
|
2005-031061 |
|
Feb 2005 |
|
JP |
|
2005/121771 |
|
Dec 2005 |
|
WO |
|
Other References
"Ultrasonic Flaw Detection Test III" 2001, Jun. 11, 2001, pp. 57-58
and pp. 117-118. cited by applicant.
|
Primary Examiner: Macchiarolo; Peter
Assistant Examiner: Miller; Rose M
Attorney, Agent or Firm: Clark & Brody
Claims
What is claimed is:
1. An ultrasonic testing method comprising the steps of: disposing
a linear array ultrasonic probe in which a plurality of transducers
are arranged in a direction orthogonal to the rolling direction of
a test object such that it is opposed to the test object; moving
the ultrasonic probe in the rolling direction of the test object
relative to the test object; and calculating the area of a defect
existing in the test object by a signal processing unit based on
testing signals output from the ultrasonic probe, wherein the step
of calculating the area of the defect by the signal processing unit
includes: a first step of performing aperture synthetic processing
on testing signals output from the ultrasonic probe so as to
generate an aperture synthetic image of the testing signals about
each section of the test object in the direction opposed to the
ultrasonic probe; a second step of extracting a maximum value of
the testing signals in the opposed direction from the aperture
synthetic image so as to generate a maximum value distribution of
the testing signals in the arrangement direction of the
transducers; a third step of calculating both ends in the width
direction of the defect in each section of the test object, based
on the maximum value distribution of the testing signals in the
arrangement direction of the transducers so as to calculate the
width of the defect in each section of the test object based on the
calculated distance between the both ends; a fourth step of
generating a maximum value distribution of the testing signals in
the rolling direction, based on the maximum value distribution of
the testing signals in the arrangement direction of the transducers
in a plurality of sections of the test object; a fifth step of
calculating the length of the defect based on the maximum value
distribution of the testing signals in the rolling direction
generated in the fourth step; and a sixth step of calculating the
area of the defect based on the length of the defect calculated in
the fifth step and the width of the defect in each section
calculated in the third step.
2. An ultrasonic testing equipment comprising: a linear array
ultrasonic probe disposed to be opposed to a test object and
movable in the rolling direction of the test object relative to the
test object, in which a plurality of transducers are arranged in a
direction orthogonal to the rolling direction; and a signal
processing unit for calculating the area of a defect existing in
the test object based on testing signals output from the ultrasonic
probe, wherein the signal processing unit comprises: an aperture
synthetic processing portion for performing aperture synthetic
processing on testing signals output from the ultrasonic probe so
as to generate an aperture synthetic image of the testing signals
about each section of the test object in the direction opposed to
the ultrasonic probe; a width direction profile arithmetic
operating portion for extracting a maximum value of the testing
signals in the opposed direction from the aperture synthetic image
so as to generate a maximum value distribution of the testing
signals in the arrangement direction of the transducers; a defect
both-ends arithmetic operating portion for calculating both ends in
the width direction of the defect in each section of the test
object, based on the maximum value distribution of the testing
signals in the arrangement direction of the transducers so as to
calculate the width of the defect in each section of the test
object based on the calculated distance between the both ends; a
length direction profile arithmetic operating portion for
generating a maximum value distribution of the testing signals in
the rolling direction, based on the maximum value distribution of
the testing signals in the arrangement direction of the transducers
in plurality of sections of the test object and for calculating the
length of the defect based on the generated maximum value
distribution of the testing signals in the rolling direction; and a
defect area arithmetic operating portion for calculating the area
of the defect based on the length of the defect calculated by the
length direction profile arithmetic operating portion and the width
of the defect in each section calculated by the defect both-ends
arithmetic operating portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ultrasonic testing method and
equipment therefor capable of measuring an area of a defect
extending in the rolling direction of a test object with high
precision and simply.
2. Description of the Related Art
To guarantee the quality of a rolled metal product (including
half-finished products) such as iron and steel products, detection
for a defect existing in a product according to an ultrasonic
testing and determination on whether or not it is acceptable are
carried out. The standard for determining whether or not any
product is acceptable is specified by for example, the dimensions
of a defect which should be detected. For example, according to API
standard 5CT, which is one of Oil Country Tubular Goods (OCTG)
related standards, it is stipulated that if any defect which
surface is not open within the steel pipe or tube (which is not
exposed on the inner and outer surfaces of the steel pipe or tube)
is detected, the area of that defect shall not be 260 mm.sup.2 or
more (API Specification 5CT/ISO 11960). The area of the defect is
an important factor for guaranteeing the quality of a product.
As a conventional method for calculating the area of any defect
quantitatively by ultrasonic testing, there have been known (A) a
method for calculating the area of the defect using the height of
echo and (B) a method for calculating the area of the defect
according to a moving distance in which defect echo appears when an
ultrasonic probe is moved, as described in Non-Patent Literature 1
("Ultrasonic Flaw Detection Test III" 2001, compiled by the
Japanese Society for Non-Destructive Inspection, Jun. 11, 2001, pp.
57-58 and pp. 117-118).
Further, (C) a method for calculating the area of the defect using
aperture synthetic processing has been proposed in Patent
Literature 1 (Japanese Laid-Open Patent Publication No.
2005-31061). Hereinafter, these methods will be described in
detail.
(A) Method for Calculating the Area of a Defect Using the Height of
Echo
When the size of a defect is smaller than the effective width of
ultrasonic beam, the area of the defect can be calculated using a
relationship that the area of the defect and the height of echo are
proportional to each other.
An echo height P.sub.R from a circular flat defect existing at a
point by a distance (distance on the central axis of a circular
transducer) x.sub.1 from the circular transducer which constitutes
the ultrasonic probe is expressed in the following equation
(1).
.times..times..times. ##EQU00001##
.times..apprxeq..pi..times..times..times..lamda..times..times..pi..times.-
.times..times..lamda..times..times. ##EQU00001.2##
where, in the above equation (1), P.sub.0 means incident sound
pressure of ultrasonic wave, .lamda. means the wavelength of
ultrasonic wave, D means the diameter of a transducer and d means
the diameter of a defect.
It is evident from the above equation (1) that the echo height
P.sub.R of the defect is proportional to .pi.d.sup.2/4 which is the
area of the defect.
On the other hand, if a test object has a sufficiently wide plane
as its bottom surface, the echo height P.sub..infin. of the bottom
surface is expressed in the following equation (2) when a distance
from the transducer to the bottom surface is x.sub.2.
.times..times..times..times..infin..apprxeq..pi..times..times..times..lam-
da..times..times. ##EQU00002##
The area of the defect can be estimated by obtaining the ratio of
the echo height P.infin. of the bottom surface and the echo height
P.sub.R of the defect according to the above equations (1) and (2)
and measuring the distances x.sub.1, x.sub.2.
However, the above equation (1) is established when the surface of
a defect is parallel to the surface of the transducer of the
ultrasonic probe. In other words, the calculation method is based
on an assumption that the surface of the defect is parallel to the
surface of the transducer of the ultrasonic probe and that a
maximum echo from the defect is received by the ultrasonic probe.
Therefore, if the surface of the defect is tilted with respect to
the surface of the transducer, the echo reflected by the defect is
hard to receive by the ultrasonic probe thereby reducing its
calculation accuracy, which is a problem. Further, the calculation
method cannot be employed if the size of the defect is larger than
the effective width of ultrasonic beam. Thus, if the test object is
a rolled material such as a steel pipe or tube and a steel sheet,
it is necessary to use an ultrasonic probe having a large
transducer for a planar defect extending in the rolling direction,
which is not realistic.
(B) Method for Calculating the Area of a Defect According to a
Moving Distance in which Defect Echo Appears by Moving the
Ultrasonic Probe
In a case where the size of a defect is larger than the effective
width of ultrasonic beam, there have been known a method for
measuring a range in which the defect echo drops from a maximum
echo height to a predetermined level by moving the ultrasonic probe
or measuring a range in which the echo height appears over a
predetermined height regardless of the maximum echo height, as an
indicative length of the defect. According to this method, the
length of the defect can be measured with relatively high precision
by selecting an ultrasonic probe having smaller transducers than
the length of the defect which is a measuring object. As for the
planar defect extending in the rolling direction of a rolled
material such as a steel pipe or tube and a steel sheet and the
like, defect dimensions (defect length) in the rolling direction
can be measured with relatively high precision according to the
method.
However, it is difficult to satisfy the prerequisite of the method
that the size of the defect is larger than the effective width of
ultrasonic beam since the dimension of the defect (defect width) in
a direction perpendicular to the rolling direction is smaller than
that in the rolling direction. The reason is that if the dimension
of the transducer is reduced, ultrasonic beam is expanded and if
the dimension of the transducer is increased, oscillated ultrasonic
beam itself is expanded.
FIG. 1 shows an example of a result of measuring the echo height by
moving ultrasonic probes whose the width of transducers are 3.5 mm
and 0.7 mm, respectively, with respect to a defect of width 1 mm in
its defect width direction at a position apart by 10 mm from the
defect (with the ultrasonic probe installed on the surface of a
test object in which the defect exists at a position of 10 mm in
depth, moving in the defect width direction). As shown in FIG. 1,
in a case where any ultrasonic probe is used, the distribution of
the echo height in the width direction exhibits a smooth shape
originating from a fact that the effective width of the ultrasonic
beam is large. If the range in which the echo height drops by 6 dB
from the maximum echo height is assumed as a defect width, the
defect width to be measured by each ultrasonic probe is 6.3 mm and
2.8 mm, which is larger than an actual defect width (1 mm).
Therefore, In the above method, even if the length of any planar
defect extending in the rolling direction, having a small width in
a direction perpendicular to the rolling direction of a rolled
material such as a steel pipe or tube and a steel sheet can be
measured with relatively high precision, the defect width is
measured to be larger than its actual width. That is, the above
method calculates the area of the defect to be excessive. As a
result, any product which is not actually defective is determined
to be defective thereby possibly reducing the yield.
(C) Method for Calculating the Area of a Defect by Aperture
Synthetic Processing.
On the other hand, Patent Literature 1 has disclosed a method in
which three-dimensional imaging data of the interior of a test
object is generated based on data collected by executing ultrasonic
flaw detection using a group of transducers arranged in a matrix
state and then this three-dimensional imaging data is processed to
automatically calculate the area of the defect. More specifically,
when the area of the defect is automatically calculated from the
three-dimensional imaging data, the three-dimensional imaging data
is seen through in each axial direction of orthogonal coordinates
to project data having a maximum value to a plane. Then, by
counting the number of meshes having a higher value than a
predetermined threshold on the projection plane, the area of the
defect is calculated. This method enables the defect to be
displayed at high resolution by employing the aperture synthetic
technique when any three-dimensional imaging data is generated.
However, there is a problem in calculation efficiency and
calculation accuracy when this method is applied to the planar
defect or the like of the rolled material. Hereinafter, this method
will be described in detail.
It has been known that the resolution of the aperture
synthetic-processing image obtained by the aperture synthetic
processing depends on an arrangement pitch of the transducer and
the size of the aperture. The size of the aperture is similar to
the entire dimension of the group of the transducers which receive
an echo at the time of the aperture synthetic processing (entire
dimension of the group of the transducers arranged in a direction
in which the aperture synthetic processing is carried out). Then,
it has been known that the smaller the arrangement pitch of the
transducers and the larger the size of the aperture (entire
dimension of the group of the transducers), the higher the
resolution becomes.
Therefore, it can be expected that the dimension of the defect is
measured in the aforementioned direction with high precision by
using the group of the transducers, the group being configured by
arranging a number of the transducers each having a minute
dimension in a direction in which the dimension of the defect is
required to be measured with high precision. However, the number of
the transducers which can be disposed is limited from the
perspective of equipment cost, because an electronic circuit
relating to exchange and processing of signals is connected to each
of these transducers and such an equipment prevalent currently
contains about 256 transducers.
As described above, to calculate the area of a defect in a rolled
material, it is necessary to measure dimensions of the defect in a
direction orthogonal to the rolling direction with high precision
because the defect is long in the rolling direction while it is
short in the direction orthogonal to the rolling direction, in
order to enhance the accuracy of calculation on the area of the
defect. When a group of transducers in which the transducers having
a minute dimension are arranged densely in a matrix state is used,
the resolution in the rolling direction is intensified more than
required, while the resolution in the direction orthogonal to the
rolling direction is dropped because the size of the aperture is
decreased and further, a range which can be measured all at once
becomes narrow. For example, to obtain a resolution of about 0.3
mm, at least the arrangement pitch of the transducers needs to be
about 0.6 mm, because the arrangement pitch of the transducers
needs to be twice or more the resolution in the aperture synthetic
processing. When the arrangement pitch of the transducers is 0.6
mm, the size of the aperture is about 0.6.times.16=9.6 mm in the
case of the group of the transducers in which 16.times.16 (=256)
transducers are arranged in a matrix state. Further, the resolution
at a point of a predetermined depth of a test object just below the
center of the group of the transducers is assumed to be .lamda./(2
sin .theta.) when the aperture angle is 2.theta. and the wavelength
of ultrasonic wave is .lamda.. For example, a steel material having
a sound velocity of 5960 m/s is employed as a test object and a
group of the transducers is placed on the surface of the test
object. If the ultrasonic testing frequency is set to 5 MHz, the
resolution at a depth of 10 mm from the surface of steel material
is about 1.4 mm, indicating that the resolution is dropped.
Additionally, a range in which the measurements in the direction
orthogonal to the rolling direction can be done all at once is
reduced to about 9.6 mm which is similar to the size of an
aperture. Therefore, it is difficult to say that the calculation
efficiency and calculation accuracy have a balance with each
other.
SUMMARY OF THE INVENTION
The present invention has been devised to solve the above problems
of the related art and an object of the present invention is to
provide an ultrasonic testing method and equipment therefore
capable of measuring the area of a defect extending in the rolling
direction of a test object with high precision and simply.
As a result of intensive studies for solving the above problems,
the inventors of the present invention have considered that the
dimension of a defect (defect length) in the rolling direction can
be calculated sufficiently according to (B) the method for
calculating the area of the defect with the moving distance in
which the defect echo appears by moving the ultrasonic probe as
with the related art described above. Then, they have considered
that the area of the defect can be measured with high precision and
simply by combining this method with a method capable of measuring
the dimension of the defect (defect width) in a direction
orthogonal to the rolling direction with high precision. The
inventors have reached an idea that the width of the defect in a
certain section can be measured with high precision by disposing a
linear array ultrasonic probe in which a plurality of transducers
are arranged in line such that the arrangement direction of the
transducers agrees with the direction orthogonal to the rolling
direction of a test object and performing aperture synthetic
processing on testing signals in the section of the test object
(section in a direction opposed to the ultrasonic probe) output
from the ultrasonic probe. If the arrangement pitch of the
transducers of the linear array ultrasonic probe is about 0.6 mm,
the size of the aperture is about 153 mm in the linear array
ultrasonic probe having 256 transducers, which is a sufficient size
for the dimension of the defect. Further, they have reached an idea
that the length of the defect can be measured simply based on a
distribution in the rolling direction of testing signals when the
ultrasonic probe is moved in the rolling direction.
The present invention has been completed based on knowledge of the
inventors. That is, the ultrasonic testing method according to the
present invention includes the steps of: disposing a linear array
ultrasonic probe in which a plurality of transducers are arranged
in a direction orthogonal to the rolling direction of a test object
such that it is opposed to the test object; moving the ultrasonic
probe in the rolling direction of the test object relative to the
test object; and calculating the area of a defect existing in the
test object based on testing signals output from the ultrasonic
probe.
The step of calculating the area of the defect has a feature in
including following first to sixth steps.
(1) First step: performing aperture synthetic processing on testing
signals output from the ultrasonic probe so as to generate an
aperture synthetic image of the testing signals for each section of
the test object in the direction opposed to the ultrasonic probe.
(2) Second step: extracting a maximum value of the testing signals
in the opposed direction from the aperture synthetic image so as to
generate a maximum value distribution of the testing signals in the
arrangement direction of transducers. (3) Third step: calculating
both ends in the width direction of the defect in each section of
the test object, based on the maximum value distribution of the
testing signals in the arrangement direction of the transducers so
as to calculate the width of the defect in each section of the test
object based on the calculated distance between the both ends. (4)
Fourth step: generating a maximum value distribution of the testing
signals in the rolling direction, based on the maximum value
distribution of the testing signals in the arrangement direction of
the transducers in a plurality of sections of the test object. (5)
Fifth step: calculating the length of the defect based on the
maximum value distribution of the testing signals in the rolling
direction generated in the fourth step. (6) Sixth step: calculating
the area of the defect based on the length of the defect calculated
in the fifth step and the width of the defect in each section
calculated in the third step.
According to the present invention, the width of the defect in each
section of the test object in the direction opposed to the
ultrasonic probe (dimension in the direction orthogonal to the
rolling direction) can be measured with high precision by the first
step to third step. Then, the length of the defect (dimension in
the rolling direction) can be measured simply by the fourth step
and the fifth step. Consequently, the area of the defect can be
measured with high precision and simply by the sixth step.
In the meantime, the "maximum value of the testing signals" in the
present invention means any of a maximum value of the testing
signal having a positive polarity and a minimum value of the
testing signals having a negative polarity (i.e., maximum value of
an absolute value of the ultrasonic signals having a negative
polarity).
Further, to solve the above problems, the present invention
provides an ultrasonic testing equipment including a linear array
ultrasonic probe disposed to be opposed to a test object and
movable in the rolling direction of the test object relative to the
test object, in which a plurality of transducers are arranged in a
direction orthogonal to the rolling direction, and a signal
processing unit for calculating the area of a defect existing in
the test object based on the testing signals output from the
ultrasonic probe, the signal processing unit executing the first
step to sixth step.
According to the ultrasonic testing method and equipment of the
present invention, the area of the defect extending in the rolling
direction of the test object can be measured with high precision
and simply.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory diagram for explaining a conventional
defect area calculating method;
FIGS. 2A and 2B are schematic diagrams each illustrating the
schematic configuration of an ultrasonic testing equipment
according to an embodiment of the present invention, where FIG. 2A
shows a block diagram of the entire configuration and FIG. 2B shows
a perspective view for explaining the arrangement of linear array
ultrasonic probes;
FIG. 3 is an explanatory diagram for explaining aperture synthetic
processing to be performed by an aperture synthetic processing
portion shown in FIGS. 2A and 2B;
FIGS. 4A and 4B are explanatory diagrams for explaining a
transmission/reception pattern of the ultrasonic probe shown in
FIGS. 2A and 2B.
FIGS. 5A to 5D are explanatory diagrams for explaining a processing
which the width direction profile arithmetic operating portion and
defect both-ends arithmetic operating portion illustrated in FIGS.
2A and 2B perform. FIG. 5A shows an example of an aperture
synthetic image generated by the aperture synthetic processing
portion. FIG. 5B shows an intensity distribution of testing signals
along the line A-A in FIG. 5A. FIG. 5C shows a width direction
profile generated by the width direction profile arithmetic
operating portion of the aperture synthetic image shown in FIG. 5A.
FIG. 5D is a diagram for explaining a method for the defect
both-ends arithmetic operating portion to calculate both ends of a
defect in the width direction based on the width direction profile
shown in FIG. 5C.
FIG. 6 shows an example of a length direction profile generated by
a length direction profile arithmetic operating portion shown in
FIGS. 2A and 2B.
FIG. 7 is an explanatory diagram for explaining a processing which
the defect area arithmetic operating portion shown in FIGS. 2 A and
2B performs.
FIG. 8 shows an example of a result of calculation of defect widths
according to the embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, an embodiment of an ultrasonic testing method and
equipment therefore according to the present invention will be
described with reference to the accompanying drawings.
FIGS. 2A and 2B are schematic diagrams each showing the schematic
configuration of the ultrasonic testing equipment according to the
present embodiment. FIG. 2A shows a block diagram showing the
entire configuration and FIG. 2B shows a perspective view for
explaining the arrangement of a linear array ultrasonic probe.
As shown in FIGS. 2A and 2B, an ultrasonic testing equipment 100 of
the present embodiment includes a linear array ultrasonic probe 1
and a signal processing unit 2 for calculating the area of a defect
F existing in a test object M based on testing signals output from
the ultrasonic probe 1.
The ultrasonic probe 1 is disposed to be opposed to the test object
M and moved in the rolling direction with respect to the test
object M, while a plurality of transducers 11 are arranged in a
direction orthogonal to the rolling direction.
The signal processing unit 2 includes a switching circuit 2A, a
pulser 2B, a receiver 2C, an amplifier 2D, an A/D converter 2E, a
waveform memory 2F, an aperture synthetic processing portion 2G, a
transmission/reception pattern control portion 2H, a width
direction profile arithmetic operating portion 2I, a defect
both-ends arithmetic operating portion 2J, a length direction
profile arithmetic operating portion 2K, a position detector 2L and
a defect area arithmetic operating portion 2M.
The switching circuit 2A is connected to each transducer 11 of the
ultrasonic probe 1. The switching circuit 2A selects a transmission
transducer 11 and a reception transducer 11 corresponding to a
predetermined transmission/reception pattern transmitted from the
transmission/reception pattern control portion 2H so as to connect
these with the pulsers 2B and the receivers 2C.
The pulser 2B applies a transmission signal to the selected
transmission transducer 11. As a result, ultrasonic wave oscillated
from the transmission transducer 11 is propagated in the test
object M, reflected by the surface of the test object M and a
defect F and received by the selected reception transducer 11. The
received testing signal is converted to digital data through the
receiver 2C, the amplifier 2D and the A/D converter 2E and recorded
in the waveform memory 2F.
The aperture synthetic processing portion 2G carries out aperture
synthetic processing to testing signals recorded in the waveform
memory 2F. At this time, information of the ultrasonic probe 1 and
the test object M (for example, a positional relationship between
the ultrasonic probe 1 and the test object M, ultrasonic testing
frequency of the ultrasonic probe 1, sound velocity in the test
object M and coupling medium, the outside diameter of the test
object M if it is a pipe or tube, and the like) and the
transmission/reception pattern stored in the transmission/reception
pattern control portion 2H are used.
FIG. 3 is an explanatory diagram for explaining the aperture
synthetic processing performed by the aperture synthetic processing
portion 2G. Upon the aperture synthetic processing, the coordinate
space of a section M1 (see FIG. 2B) of the test object M in the
direction opposed to the ultrasonic probe 1 is divided to meshes.
Then, the value of a testing signal recorded in the waveform memory
2F is obtained and input to each mesh. When determining a value to
be obtained, first, the transmission transducer 11 (transducer P in
FIG. 3) and the reception transducer 11 (transducers Ra and Rb in
FIG. 3) which attracts attention are determined from the
transmission transducers 11 and reception transducers 11 selected
depending on the transmission/reception pattern. Then, a
propagation path WI of ultrasonic wave from the transmission
transducer P to the mesh which attracts attention and propagation
paths WRa and WRb of ultrasonic wave from the mesh which attracts
attention to the reception transducers Ra and Rb are determined.
The determination of these propagation paths WI, WRa, and WRb is
carried out by selecting an incident point and an outgoing point of
the ultrasonic wave so that the propagation paths connecting the
transducers P, Ra, and Rb with the incident points or outgoing
points of the ultrasonic wave on the test object M and the
propagation path connecting the incident point or the outgoing
point of the ultrasonic wave on the test object M with the mesh
which attracts attention satisfy the Snell's law or Fermat's
theorem, based on the positional relationship between the
transducers P, Ra, and Rb and the test object M, the sound velocity
in the coupling medium and the test object M, and the like. Values
of signals corresponding to a propagation time (Ta) of the
propagation paths WI and WRa are obtained from testing signals at
the reception transducer Ra recorded in the waveform memory 2F and
input to the mesh which attracts attention. Then, values of signals
corresponding to a propagation time (Tb) of the propagation paths
WI and WRb are obtained from the testing signals at the reception
transducer Rb recorded in the waveform memory 2F and input to the
same mesh which attracts attention (added). The above-described
processing is carried out based on combinations of all the
transmission transducers 11 and reception transducers 11 selected
depending on the transmission/reception pattern so as to determine
the value of a testing signal to be input to the mesh which
attracts attention. Then, this processing is carried out on all the
meshes so as to generate the aperture synthetic image of a section
M1. Because the ultrasonic probe 1 is moved in the rolling
direction with respect to the test object M, a plurality of the
aperture synthetic images are generated for a plurality of section
of the test object M. More specifically, the aperture synthetic
images are generated for the plurality of sections (for example,
sections obtained by a predetermined relative movement)
corresponding to relative positions between the ultrasonic probe 1
and the test object M, detected by the position detector 2L.
As shown in FIG. 4A, a group of the transducers (part of or all of
the transducers 11 which constitute the ultrasonic probe 1) driven
as the transmission transducer 11 and the reception transducer 11
is selected and the transmission transducer 11 and the reception
transducer 11 are changed over successively in the selected
transducer group so as to obtain one aperture synthetic image for
the section of one test object M. As shown in FIG. 4B, the same
processing is carried out by changing over the transducer group to
be selected within the same section so as to obtain a plurality of
the aperture synthetic images in the same section (finally, the
values of respective meshes of these plurality of aperture
synthetic images are summed up so as to obtain one aperture
synthetic image).
The width direction profile arithmetic operating portion 2I
extracts a maximum value of the testing signals in an opposed
direction between the ultrasonic probe 1 and the test object M
(depth direction of the test object M) about the aperture synthetic
image of each section of the test object M generated by the
aperture synthetic processing portion 2G as described above so as
to generate a maximum value distribution (hereinafter referred to
as a "width direction profile" as required) of the testing signals
in the arrangement direction of the transducer 11 (width direction
of the defect F).
The defect both-ends arithmetic operating portion 2J calculates
both ends in the width direction of the defect F in each section of
the test object M based on a width direction profile generated by
the width direction profile arithmetic operating portion 2I so as
to calculate the width of the defect F in each section of the test
object M based on the distance between the calculated both
ends.
A processing executed by the width direction profile arithmetic
operating portion 2I and the defect both-ends arithmetic operating
portion 2J will be described more in detail with reference to FIGS.
5A to 5D.
FIGS. 5A to 5D are explanatory diagrams for explaining the
processing executed by the width direction profile arithmetic
operating portion 2I and the defect both-ends arithmetic operating
portion 2J. FIG. 5A shows an example of the aperture synthetic
image generated by the aperture synthetic processing portion 2G.
FIG. 5B shows an intensity distribution of the testing signals
along the line A-A in FIG. 5A. FIG. 5C shows a width direction
profile generated by the width direction profile arithmetic
operating portion 2I of the aperture synthetic image shown in FIG.
5A. FIG. 5D is a diagram for explaining a method for calculating
both ends in the width direction of the defect F by means of the
defect both-ends arithmetic operating portion 2J based on the width
direction profile shown in FIG. 5C.
The width direction profile arithmetic operating portion 2I reads a
value of a testing signal input to a certain mesh located in each
width direction (arrangement direction of the transducers 11)
position successively about the aperture synthetic image shown in
FIG. 5A along a depth direction (in an opposed direction between
the ultrasonic probe 1 and the test object M) and extracts its
maximum value to plot it at each position in the width direction.
For example, as for the width direction position along the line A-A
in FIG. 5A, the values of the testing signals input to each mesh
are read successively along the line A-A and its maximum value A'
is extracted and plotted at a corresponding position in the width
direction. At this time, the width direction profile arithmetic
operating portion 2I stores coordinates (width direction position,
depth direction position) of the mesh in which the extracted
maximum value is input.
By repeating the above-described processing for all the positions
in the width direction, a width direction profile having a maximum
value distribution of the testing signals in the width direction
(arrangement direction of the transducers 11) of the defect F is
generated as shown in FIG. 5C. The generated width direction
profile and the coordinates of the mesh in which the extracted
maximum value is input are input to the defect both-ends arithmetic
operating portion 2J.
The defect both-ends arithmetic operating portion 2J calculates a
range in which the maximum value drops by a predetermined dB from a
maximum value Mn of the width direction profile or a range in which
the maximum value of the testing signals exceeds a predetermined
threshold about the width direction profile (FIG. 5C) generated by
the width direction profile arithmetic operating portion 2I. In the
example shown in FIG. 5C, a range W in which the maximum value
drops by 6 dB from the maximum value Mn is calculated. Then, as
shown in FIG. 5D, the defect both-ends arithmetic operating portion
2J reads the coordinates of the mesh in which the maximum value
corresponding to both ends of the calculated range W is input so as
to adopt them as the coordinates of both ends ELn, ERn of the
defect F. Then, the distance between both ends ELn, ERn of the
defect is calculated so as to adopt it as the width of defect
F.
The width of the defect F in each section of the test object M is
calculated by the above-described processing.
The length direction profile arithmetic operating portion 2K
generates a maximum value distribution (hereinafter referred to as
a "length direction profile" as required) of the testing signals in
the rolling direction (length direction of the defect F) from the
width direction profile of the plurality of sections of the test
object M related with a relative position between the ultrasonic
probe 1 detected by the position detector 2L and the object
material M. More specifically, the maximum values Mn (see FIG. 5C)
of the width direction profile in each section are plotted at
positions in the length direction (rolling direction) of a rolling
object material M correlated with each section to generate the
length direction profile as shown in FIG. 6.
Then, the length direction profile arithmetic operating portion 2K
calculates a length of the defect F based on the length direction
profile. More specifically, a range in which the maximum value
drops by only the predetermined dB from the maximum value of the
length direction profile or a range in which the maximum value Mn
of the testing signal exceeds the predetermined threshold is
calculated as the length of the defect F.
The defect area arithmetic operating portion 2M calculates the area
of the defect F based on the length of the defect F calculated by
the length direction profile arithmetic operating portion 2K and
the width of the defect F in each section calculated by the defect
both-ends arithmetic operating portion 2J. More specifically, as
shown in FIG. 7, a sum of products of the width Wn of the defect F
calculated about a section within a range corresponding to the
length of the defect F and a distance .DELTA.L in the rolling
direction (length direction of the defect F) between the sections
is calculated within a range corresponding to the length of the
defect F so as to calculate the area of the defect F.
According to the ultrasonic testing method using the ultrasonic
testing equipment 100 of this embodiment, the area of the defect F
extending in the rolling direction of the test object M can be
measured with high precision and simply.
Examples
Hereinafter, the present invention will be described more in detail
by indicating examples.
The ultrasonic test was carried out by an ultrasonic testing
equipment of the present invention whose schematic configuration
was shown in FIGS. 2A and 2B in order to find a defect in a flat
bottom groove (tilted by 10.degree. with respect to the horizontal
direction of the flat panel, 3.6 mm in width and 20 mm in length)
in the flat panel. A linear array ultrasonic probe having an
ultrasonic testing frequency of 5 MHz, a transducer arrangement
pitch of 0.5 mm, and 64 transducers, and in which the length of the
transducer in a direction orthogonal to the arrangement direction
was 6 mm was used. The aperture synthetic image was generated each
time when the ultrasonic probe and a test object were moved by 1 mm
relative to each other.
FIG. 5A shows an example of the aperture synthetic image obtained
by this embodiment. To obtain the aperture synthetic image,
ultrasonic wave was sent by any one of transducers and received by
the 64 transducers and then, the transmission transducer was
changed over successively from a first transducer up to 64.sup.th
transducer. A width direction profile shown in FIG. 5C was
generated for this aperture synthetic image, both ends in the width
direction of the defect was calculated as shown in FIG. 5D and
then, the width of the defect in each section of the flat panel was
calculated according to the calculated distance between the both
ends. The defect width calculated about the aperture synthetic
image in FIG. 5A was 3.2 mm. This value was calculated with high
precision although it was calculated to be slightly smaller than an
actual defect width of 3.6 mm.
FIG. 6 shows a length direction profile obtained by this
embodiment. A range in which the defect width drops by 6 dB from
the maximum value of the length direction profile was calculated as
the length of the defect. The calculated defect length was 23 mm
and although it was slightly larger than the actual defect length
of 20 mm, it can be said that the defect length could be calculated
with high precision.
The sum of products of the defect width calculated about a section
within a range corresponding to the defect length and a distance (1
mm) in the rolling direction (direction of the defect length)
between the respective sections is calculated within the range
corresponding to the defect length so as to calculate the area of
the defect. The calculated area of the defect was 81 mm.sup.2 and
it is made evident that the defect can be measured with an error of
about +13% the actual defect area of 72 mm.sup.2.
FIG. 8 shows a result of calculation of the widths of flat bottom
holes 2.0 mm and 1.0 mm in width, each having a different depth in
the flat panel, using the ultrasonic testing equipment of this
embodiment. As shown in FIG. 8, it is evident that the width of the
defect can be calculated with high precision regardless of a depth
position of the defect (flat bottom hole).
The area of the flat bottom groove (tilted by 10.degree. with
respect to the horizontal direction of the flat panel, 3.6 mm in
width and 20 mm in length) in the flat panel was calculated as a
defect using the ultrasonic testing equipment of this embodiment.
Further, the area of the same defect was calculated as a
comparative example using an ordinary ultrasonic probe. More
specifically, the ultrasonic probe was moved in the length
direction and width direction of the defect and the length and
width of the defect were calculated according to a moving distance
in which a defect echo appears. Consequently, the area of the
defect was calculated (which is similar to the above-described
related art (B)). Table 1 shows its result.
TABLE-US-00001 TABLE 1 Result of area Defect area measuring method
Specification of ultrasonic probe Defect actual area measurement
Error Present invention Ultrasonic testing frequency: 5 MHz 36
mm.sup.2 41 mm.sup.2 +13.9% (width direction aperture synthetic +
Arrangement pitch: 0.5 mm Width: 1.8 mm length direction scanning)
Number of transducers: 64 ch Length: 20 mm Length: 6 mm Comparative
example Ultrasonic testing frequency: 5 MHz 62 mm.sup.2 +72.2%
(width direction scanning + Transducer diameter: 6.35 mm length
direction scanning)
As indicated in Table 1, according to the present invention, it is
evident that the area of the defect can be calculated with higher
precision than the related art.
* * * * *